Ankle exercise device



FIG. 1 is a front perspective view of the ankle exercise device showing our new design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a left side elevation view thereof;

FIG. 5 is a right side elevation view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken lines shown in the drawings illustrate portions of the ankle exercise device that form no part of the claimed design. 

CLAIM The ornamental design for an ankle exercise device, as shown and described. 